I use Karabiner and Seil which are great, but unless you are using an Apple keyboard with a numeric keyboard, you don't get a right-control key, which will matter for many of the most used commands for emacs.
For me, when recently trying to remap the left-shift key I found out that it was not a problem for the supposed best practice of using it for C-g/x/c etc, but that instead I had been using a worse practice for typing ":" or """ when the wrong characters turned up al over the place.
Anyway, I suppose the left option key would be pretty good to map to control for emacs, since it's rarely more needed than the right option key.
For me, when recently trying to remap the left-shift key I found out that it was not a problem for the supposed best practice of using it for C-g/x/c etc, but that instead I had been using a worse practice for typing ":" or """ when the wrong characters turned up al over the place.
Anyway, I suppose the left option key would be pretty good to map to control for emacs, since it's rarely more needed than the right option key.